Closure-Supervenience
If a physical event p has a cause c occurring at a time t, then p has a physical cause p’ such that 1) p occurs at t and 2) p is a supervenience base of c.
This principle could be given a justification similar to the one we gave Closure-Overdetermination: it could be argued that if the principle is not true, absurdly pervasive overdetermination will follow (unless mental events happen to be identical to physical events—a possibility we will consider later). For lack of space, we leave working out the exact justification for Closure-Supervenience, as well as how Kim’s second argument could be completed using it, as an exercise for the reader.